/Engine/Source/Runtime/Engine/Classes/Engine/World.h
Sets whether or not this world is ticked by the engine, but use it at your own risk! This could have unintended consequences if used carelessly. That said, for worlds that are not interactive and not rendering, it can save the cost of ticking them. This should probably never be used for a primary game world.
void SetShouldTick ( const bool bInShouldTick )